Supplemental heater unit for air conditioner of the dual blower type

ABSTRACT

A supplemental heater unit for an air conditioner of the dual blower type, provides reduced air delivery while the heater is energized. The heater unit has an air casing with separate inlets from the two blowers. When only one blower of the air conditioner is powered, an atmospheric damper closes automatically across the inlet from the unpowered blower, preventing re-circulation back to the air conditioner cabinet and thus providing a positive controlled lower rate of air delivery across a resistance heater within the air casing and to the room space.

United States Patent 1191 1111 3,731,656 Becker 1 1 May I, 1973 SUPPLEMENTAL HEATER UNIT FOR 3,566,614 3/1971 lmral ..62/426' AIR CONDITIONER OF THE DUAL 3,029,332 4/1962 Cotts ..165/64 x 3,098,145 7/1963 Raymond ..219/374 X BLOWER TYPE 2,839,659 6/1958 Colts et a1. ..219/37O X [75] Inventor: Edward A. Beckerg'Ferguson, Mo. 2,401,560 6/1946 Graham Ct 111.; ..165/29 X [73] Assigheez Intertherm, Inc. St. Louis MO. 3,164,715 l/1965 Colts 3.219/367 UX [22] Filed; Dec. 6, 1971 7 Primary E.ram l'ner-A. Bartis 1 pp NO I 204 998 Attorney-Jerome A. Gross [57] ABSTRACT [52] 7 g 4 A supplemental heater unit for an air conditioner of 51 l l65l/ l6 i 3g 5 the dual blower type, provides reduced air delivery {58% F gz' d o' 'g' lgl l0 F2 6 14/ 4 1 2 6 while the heater is energized. The heater unit'has an [56] References Cited UNITED STATES PATENTS 2,776,118 1/1957 Davis ..165/24 2,893,639 .-7/1959 Martin ..2l9/374 UX air casing with separate inlets from the two blowers. When only one blower of the air conditioner is powered, an atmospheric damper closes automatically across the inlet from the unpowered blower, preventing re-circulat'ion back to the air conditioner cabinet and thus providing a positive controlled lower rate of air delivery across a resistance heater within the air casing and to the room space.

5 Claims, 3 Drawing Figures Patented May l, 1973 2 Sheets-Sheet 1 SUPPLEMENTAL HEATER UNIT FOR AIR CONDITIONER OF THE DUAL BLOWER TYPE BACKGROUND OF THE INVENTION Certain small air conditioning units, for example, window units, have been equipped with heater coils, which may be switched on when the compressor is switched off. They utilize the air conditioners air delivery system to deliver heated air.

Air conditioning units may be located remotely from the room space to be air conditioned and connected thereto by ducts. Such an air conditioner unit, of a type especially suited for mobile homes, is shown in US. Pat. No. 3,566,614 to Imral. In it, air from the room space passes from a return duct into a remotely located air conditioner cabinet, and is cooled in a space open to two separate blowers, each leading to its own air delivery outlet. Flexible air delivery ducts connected to these outlets deliver the cooled air to spaced-apart portions of a mobile home.

The purpose of the present invention is to provide a supplemental heater unit for such a remote, dual blower type air conditioner, to operate at a reduced air delivery rate. The rapid rate at which cooled air may be circulated through a room space is not well suited for heating; persons feel more comfortable when heated air is introduced at relatively slow velocity. While a manually operated damper might be used to reduce the, rate of air delivery, its use would be inconvenient; and an electrically operated damper would add expense.

SUMMARY OF THE INVENTION In the present invention a supplemental heater unit incorporates a simple damper of the atmospheric type, to reduce the rate of air delivery while a resistance heater is energized. The damper is closed by a pressure differential which results from powering one of the two blowers of the air conditioner while the other blower is unpowered. The damper prevents recirculation of the air from the heaters air casing back to the air conditioner cabinet; this assures positive delivery of air at the reduced rate. When the heater is switched off and the air conditioner operated for cooling, using both blowers, the pressure differential ceases and the damper opens automatically.

Summarized briefly, the present heater unit includes a walled air casing with first and second air inlets, to be connected to the first and second blower outlets of such an air conditioner. An electrical resistance heater is positioned within the air casing between the inlets and a pair of outlets; ducts to the room space are connected to these instead of to the air conditioner itself. A flat damper plate, hingedly supported above the inlet from the second blower of the air conditioner, is closed when this blower is de-energized and the first blower is operated. The damper plate positively prevents flow back from the heater air casing to the air conditioner cabinet. The inlets of both blowers in such an air conditioner are open to the same space within the air conditioner cabinet; powering the first blower to drive air into the air casing exerts a suction which is communicated through the outlet of the unpowered second blower to the other side of the damper. Thus, a simple damper of the atmospheric type will serve, with this type of dual blower air conditioner, to provide positive flow of heated air to the room space at a fixed reduced rate, and prevent re-circulation from the air casing back to the air conditioner cabinet.

The suction which closes the damper is so great that it may be broadened to partially block the flow from the powered blower, thus to effect an even greater reduction in air delivery.

The rate of air flow, measuredin cubic feet per minute, does not vary directly with the blower power supplied. Restrictions in the flow path, such as registers in the system and the size of the return duct, result in a disproportionately high air delivery at reduced blower capacity. Thus even with the present invention, it is normally not possible to cut the rate of air delivery in half. However, by reducing the rate of air delivery by 25 percent, for example, the effective temperature rise, over room temperature, may be increased from 27 to 36. This difference is important to body comfort; for a 27 rise over ordinary room temperature might result in delivery of air at below body temperature, whereas a 36 rise would assure delivery of air at above body temperature.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic plan view of a supplemental heater unit embodying the present invention, attached to a dual blower air conditioner unit of the type heretofore referred to. Arrows show flow of heated and return FIG. 2 is an enlarged perspective view of the heater unit of FIG. 1, with the walls partially broken away. Phantom lines show the damper in open position during normal air conditioning operation.

FIG. 3 is an electrical diagram showing the heater unit wired into the air conditioner unit of FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT A dual blower air conditioner, of the type suitable for use with the present invention, is shown at the left side of FIG. 1. This type of air conditioner, described in detail in U.S. Pat. No. 3,566,614, is especially suited for use with mobile homes; its low overall height permits it to be positioned beneath a mobile home; its dual outlets permit delivery of cooled air to the opposite ends of the mobile home; and the use of flexible air delivery and return ducts permits the unit to be easily installed and serviced.

The arrangement of the components of this type of dual blower air conditioner is shown schematically in FIG. 1. A rectangular cabinet a is separated by an S- shaped vertical separator wall b into an air handling side 0 and a condenser side d, the latter containing a condenser coil 2, two motors f and g and their condenser cooling fans h. Shafts from the motors f and g opposite to the fans h extend through the vertical separator wall b to mount centrifugal blowers j, k whose respective air delivery ducts m, n lead side by side to first and second adjacent circular air outlets p, qin the forward wall r. An air return inlet s permits return air to flow into the air handling side c of the cabinet, through an evaporator coil t, and thus into the air space which supplies both blowers j, k. A compressor u is positioned as shown; and the components described are operably connected with other conventional air conditioning components. When the compressor u is energized, both motors f, g are powered; and air will be delivered by the blowers j, k through their respective delivery ducts m, n at equal delivery rates.

The supplemental heating unit of the present invention is interposed at the air conditioner outlets p, q in such manner as not to interfere with the normal air conditioning mode of operation; yet the combination will supply heated air at a lesser, predetermined delivery rate, to assure an adequate temperature rise.

Referring to FIG. 2 the present supplemental heater unit includes a walled air casing, generally designed 10, formed like a rectangular metal box, lined with conventional thermal insulation material, and with an added circuit box 11 on one of its vertical side walls 12. The

side walls 12, together with top and bottom walls 13, 14, provide a conduit for the passage of air from a vertical inlet wall 16 to a vertical outlet wall 17. Air delivery ducts v, w, shown in phantom lines in FIG. 2, are attached to outlets 18, 19 in the outlet wall 17 instead of to the air conditioner outlets p,

In the inlet wall 16, at the same spacing as that of the air conditioner outlets p, q, first and second air inlets 21, 22 are provided, having means, such as a simple edge flange 23, to make sealed connections to the air conditioner outlets p, q. Interposed between the inlets 21, 22 to the heater casing and its outlets 18, 19 (preferably immediately in advance of the outlets 18, 19) is an electrical heater generally designated 25. This is shown as a simple lattice-like resistance heater, which occupies the greater part of the interior area across the air casing 10 and which permits the flow of air therethrough without substantial interruption. This result follows, in the embodiment shown, because the cross-section of the air casing 10 is amply larger than the combined cross-sections of the air outlets 18, 19;

the air passing through it may slow, to take up heat from the resistance heater 25, and then again resume its original flow rate as its passes into the delivery ducts At first consideration, it might be thought that a positive cut in the rate of air delivery could be achieved merely by cutting off one of the blowers j, k. This does not follow; if only the first blower j were powered, the drop in air pressure within the air-handling side c of the air conditioner cabinet a would be communicated to the air casing 10 through the duct of the second blower k, to suck back to the air handling side c part of the air delivered by the first blower j. Without some means to close off the second air inlet 22 or the duct n leading to it, the air delivery from the first blowerj alone would drop to some unpredictable rate and heated air might enter the air conditioner cabinet a. The remote location of the air conditioning and heating units precludes use of a mechanical damper; and to provide an electrically controlled damper would add expense and mechanical complications.

To sole this problem I provide damper means of the atmospheric type, generally designated 30. The embodiment illustrated in FIG. 2 includes a metal damper plate 31 larger than the second air inlet 22. It is hinged, as hereinafter described, to blow upward when the second blower k is powered and to be drawn sealedly against the inlet opening 22 when there is a pressure drop in the air delivery duct n leading to it, compared with the pressure in the air casing 10.

In the simple embodiment illustrated, the damper plate 3l has adhered along its upper edge the lower margin of a horizontal strip of flexible rubber 32. The upper margin of rubber strip 32 is adhered to the downward projecting leg 33 of an angle 34 mounted beneath the top wall 13 of the air casing 10 immediately inward of the inlet wall 16. The width of the flexible rubber strip 32 between its upper and lower margins so adhered, serves as substantially frictionless hinge means to permit the damper plate 31 to blow open from its closed position, as shown in FIG. 2 in solid lines, to its open position shown in phantom lines.

The damper plate 31 maybe made of such width as to close only the second air inlet 22. In the embodiment illustrated the plate 31 is made somewhat broader, to extend over 15 percent to 20 percent of the area of the first air inlet 21, thus to reduce the air delivery rate to roughly percent of its rate for air conditioning and to effect I an increase in temperature rise, as hereinabove explained. While it is not feasible to use a hinged plate 31 to close off as much ashalf of the first air inlet 21, the pressure differential exerted across the second air inlet 22 is great enough to hold the damper plate 31 firmly closed across a substantial but minor portion of the first air inlet 21, despite the flow of air past the projecting edge 35 of the plate 31.

To direct the air flow to both the casing outlets l8, 19 when only the first inlet 21 is open, a vane 36, curved in plan form, is optionally provided to extend from the center of the inlet 21 aft and curvedly a short distance toward the second air outlet 19. In the emdodiment illustrated, the vane 36 is supported by several angles 37. A corner 38 of the damper plate 31 is cut off roundedly, as shown in FIG. 2, to provide clearance from the vane 36 when the damper plate 31 raises to open position.

FIG. 3 shows a wiring diagram in which the components of the heating unit 10 heretofore described are operably interrelated, by conventional means, with a dual blower air conditioner of the type heretofore described. The left side of the drawing shows the elements within the air conditioner cabinet a; the right side shows those within the heater unit circuit box 11. Current from a 230 volt power source is supplied to a double pole relay-operated cooling contactor 41 and also to a 24 volt transformer 42. One lead from the transformer is connected to the relay coil of the cooling contactor 41 and also to a similar relay coil in a relay 43 for the motorfto operate in the heating mode. An extension of this 24 volt circuit, shown in dashed lines, extends from the air conditioner cabinet 0 to connect to the relay coil of a heating contactor 44, located in the circuit box 1 l of the heater unit.

The other lead from the 24 volt transformer 42 is connected to a combination room space temperature control, including a cooling thermostat 46 and a heating thermostat 47. The user selects which of the thermostats 46, 47 is put into circuit. Assuming that the cooling mode is employed, the cooling contactor 41 will be closed on a temperature rise above the setting of the cooling thermostat 46. Closing of its contacts will supply power from a 230 volt source through parallel connections to the motors f and g of the first and second blower j, k, respectively, and will also power the compressor u. On temperature drop, all these units will be de-energized.

When the system is operated in the heating mode,

the user causes the thermostat 47 to be put into circuit. 1

On temperature drop, current from the transformer 42 will be supplied to the coil of the relay 43 for the motor f and also, through the wiring sketched, to the heating contactor 44 in the air casing 10. The relay coil in the heating contactor 44 is in series with a temperature control 49 of conventional construction. A separate 230 volt circuit leads through a heating contactor 44 and through the resistance heater 25, which is in series circuit with it. Hence, when the room temperature is below the setting of the heating thermostat 47, the 24 volt current actuates the relay in the heating contactor 44, thereby to deliver the 230 volt current to the resistance heater 25. Current through the heating thermostat 47 will also have actuated the relay 43, causing the 230 circuit in the cabinet a to be made through the motor f only as illustrated. In this manner, power will be supplied to the blower j while the resistance heater 25 is energized.

it is to be understood that conventional elements such as fuses, junction boxes, etc. are employed in the usual manner; and that modifications in circuitry to meet conventional needs will be obvious to those skilled in the art.

I claim:

1. In an air conditioner of the type having a cabinet and first and second blowers operable simultaneously with or separately from each other and whose inlets are open to each other within the cabinet, such blowers having separate outlets, the improvement comprising a heater unit including a walled air casing having first and second air inlets and means thereat to connect to such first and second blower outlets,.

drop within such air conditioner cabinet will close said damper means automatically and prevent recirculation to the cabinet of such air conditioner.

2. The improvement as defined in claim 1, wherein the heating means comprises an electrical resistance heater, together with electrical switching and circuitry means to energize the said resistance heater and simultaneously to operate such first blower only if the air conditioner, without cooling.

3. The heater unit as defined in claim 1, wherein the said second air inlet is in a vertical wall of the air casing, and

the damper means comprises a flat damper plate closable against said inlet and supported by hinge means thereabove and closely adjacent to the inner surface of said vertical wall.

4. The heating unit as defined in claim 1, wherein said air inlets are positioned side by side in a vertical wall of the air casing, and the damper means lS a plate having upper edge hinge support means,

the plate being of such width and so positioned that when closed against said second air inlet it extends across a minor portion of said first air inlet.

5. For use with an air conditioner of the type having a cabinet and first and second blowers operable simultaneously with or separately from each other and whose inlets are open to each other within the cabinet, such blowers having separate side-by-side outlets,

a supplemental heater unit comprising a walled air casing having a vertical wall penetrated by side-by-side first and second air inlets,

air casing outlet means, and

. heating means within the air casing interposed between said first air inlet and the outlet means, the heater unit being characterized in having damper means inwardly adjacent .to said second air inlet, toclose said second air inlet responsive to suction external to said second air inlet created by said first blower, v

the damper means being a plate having upper edge hinge support means,

the plate being of such width and so positioned that when closed against said second air inlet it extends across a minor portion of said first air inlet. 

1. In an air conditioner of the type having a cabinet and first and second blowers operable simultaneously with or separately from each other and whose inlets are open to each other within the cabinet, such blowers having separate outlets, the improvement comprising a heater unit including a walled air casing having first and second air inlets and means thereat to connect to such first and second blower outlets, respectively, air casing outlet means, and heating means within the air casing interposed between said first air inlet and the outlet means, the heater unit being characterized in having damper means inwardly adjacent to said second air inlet, to close said second air inlet responsive to suction external to said second air inlet created by said first blower, whereby on powering such first air conditioner blower while the second is unpowered, a pressure drop within such air conditioner cabinet will close said damper means automatically and prevent re-circulation to the cabinet of such air conditioner.
 2. The improvement as defined in claim 1, wherein the heating means comprises an electrical resistance heater, together with electrical switching and circuitry means to energize the said resistance heater and simultaneously to operate such first blower only if the air conditioner, without cooling.
 3. The heater unit as defined in claim 1, wherein the said second air inlet is in a vertical wall of the air casing, and the damper means comprises a flat damper plate closable against said inlet and supported by hinge means thereabove and closely adjacent to the inner surface of said vertical wall.
 4. The heating unit as defined in claim 1, wherein said air inlets are positioned side by side in a vertical wall of the air casing, and the damper means is a plate having upper edge hinge support means, the plate being of such width and so positioned that when closed against said second air inlet it extends across a minor portion of said first air inlet.
 5. For use with an air conditioner of the type having a cabinet and first and second blowers operable simultaneously with or separately from each other and whose inlets are open to each other within the cabinet, such blowers having separate side-by-side outlets, a supplemental heater unit comprising a walled air casing having a vertical wall penetrated by side-by-side first and second air inlets, air casing outlet means, and heating means within the air casing interposed between said first air inlet and the outlet means, the heater unit being characterized in having damper means inwardly adjacent to said second air inlet, to close said second air inlet responsive to suction external to said second air inlet created by said first blower, the damper means being a plate having upper edge hinge support means, the plate being of such width and so positioned that when closed against said second air inlet it extends across a minor portion of said first air inlet. 